Your lighting and power accessories will almost certainly need new circuits, which mean having sufficient spare fuseways or breakers at the electric panel, or extending the existing service panel. If you intend extending your central heating system, check that the boiler has the extra capacity.
In general, you will probably have to re-route pipes and cables already in the attic.
Attic conversion work should not be undertaken lightly since major structural alterations to the roof are inevitable. That is why it is essential to employ professionals to carry out at least all the initial design work, loading calculations and the necessary structural alterations. Then, if you want to save money, do the less critical parts of the job yourself: building the dividing partitions, cladding the floor and ceiling, installing the electrical circuits and pipe work.
If you do intend carrying out these tasks yourself, and you have any doubts at all regarding your ability to do so, then consult an expert in the particular area. In the final analysis, it may save much frustration, time and cost.
What the job involves
The weight of the floor, partition walls and ceiling of an attic conversion can be quite considerable and that is without the loading imposed by the framework for a dormer and, of course, the furnishings added to the completed rooms. So the very first job that is done when converting the loft is to build a supporting structure that will be able to carry this loading and also provide partial support to the roof, if parts of its original framework have been removed.
It is most unlikely that the original attic joists will be capable of providing the necessary extra support. There are two ways in which a strong floor frame can be made: either extra joists of the same size as the originals are fitted between them, or a completely separate structure is built on top of them, being supported directly by the load-bearing walls. Of the two, the latter is preferable, since it will insulate the rooms below from noise and vibration from the rooms above. It will also prevent damage to the ceiling during the construction stage. However, the available headroom will be reduced.
The separate framework will consist of strong wooden beams called trimmers placed around the edges and at strategic points joists will be fitted between them on metal hangers. Where trimmers and joists pass over intermediate loadbearing walls they are packed out with wood blocks for support.
Once this framework is in place, the necessary modifications can be made to the roof itself – adding extra support struts, dormer frameworks and even, in some cases, loadbearing wood-framed partitions.
The floor is normally clad with tongued-andgrooved plywood sheets — a quickly-laid, flat floor.
It is possible to buy standard size flights of stairs, either of the closed or open tread type and, if at all possible, these should be chosen to save on the expense of having stairs specially made to fit. It may be necessary to add a trimmer joist to the floor at the foot of the stairs for extra strength; another trimmer will be needed in the attic floor to support the top. The opening for the new stairs will be quite large and roomy, requiring several original attic joists to be cut through. Their ends must be supported from the new framework with trimmer joists or metal hangers.
The staircase itself may need cladding along the underside with gypsum board, unless it is of the open-tread variety.
Joists for the ceiling can be nailed- between the original rafters, and if a dormer is fitted they are bolted in place and carried through to support the dormer roof.
The internal walls can be lightweight stud partitions. The frames should be nailed together flat on the floor and then lifted into position where they can be nailed to the floor joists, the ceiling joists and to the rafters or other parts of the structure. Always notch the frameworks to fit over the existing roof members, not the other way round otherwise you will weaken the roof.
While the ceiling and partition frameworks are bare, you can fit all the electrical accessory mounting boxes to battens nailed in place and run in all the cables and any pipe work. Then cut insulation material to fit between the studs and bracing of the walls, the joists of the ceiling and the original rafters.
Clad the walls and ceilings with foil-backed gypsum- board. This will help insulate the rooms and prevent moisture from passing through the walls into the roof space. The final job is to plaster the walls and decorate.
You will need to be able to get to the rest of the roof for repairs and maintenance to water tanks and pipe work, in addition to using it for storage purposes.
To this end, hatches should be built into the partition frameworks. They can be fitted with plywood panels held by magnetic catches and trimmed with molding.